allways initialize all variables to something safe
the def->type->type arrangement is really silly.
return type checking
parm count type checking
immediate overflow checking
pass the first two parms in call->b and call->c
*/
/*
comments
--------
// comments discard text until the end of line
/ * * / comments discard all enclosed text (spaced out on this line because this documentation is in a regular C comment block, and typing them in normally causes a parse error)
Names are a maximum of 64 characters, must begin with A-Z,a-z, or _, and can continue with those characters or 0-9.
There are two levels of scoping: global, and function. The parameter list of a function and any vars declared inside a function with the "local" statement are only visible within that function,
immediates
----------
Float immediates must begin with 0-9 or minus sign. .5 is illegal.
A parsing ambiguity is present with negative constants. "a-5" will be parsed as "a", then "-5", causing an error. Seperate the - from the digits with a space "a - 5" to get the proper behavior.
12
1.6
0.5
-100
Vector immediates are three float immediates enclosed in single quotes.
'0 0 0'
'20.5 -10 0.00001'
String immediates are characters enclosed in double quotes. The string cannot contain explicit newlines, but the escape character \n can embed one. The \" escape can be used to include a quote in the string.
"maps/jrwiz1.bsp"
"sound/nin/pain.wav"
"ouch!\n"
Code immediates are statements enclosed in {} braces.
Parenthesis can be used to alter order of operation.
The & and | operations perform integral bit ops on floats
A built in function immediate is a number sign followed by an integer.
#1
#12
compilation
-----------
Source files are processed sequentially without dumping any state, so if a defs file is the first one processed, the definitions will be available to all other files.
The language is strongly typed and there are no casts.
Anything that is initialized is assumed to be constant, and will have immediates folded into it. If you change the value, your program will malfunction. All uninitialized globals will be saved to savegame files.
Functions cannot have more than eight parameters.
Error recovery during compilation is minimal. It will skip to the next global definition, so you will never see more than one error at a time in a given function. All compilation aborts after ten error messages.
Names can be defined multiple times until they are defined with an initialization, allowing functions to be prototyped before their definition.
void() MyFunction; // the prototype
void() MyFunction = // the initialization
{
dprint ("we're here\n");
};
entities and fields
-------------------
execution
---------
Code execution is initiated by C code in quake from two main places: the timed think routines for periodic control, and the touch function when two objects impact each other.
There are three global variables that are set before beginning code execution:
entity world; // the server's world object, which holds all global
// state for the server, like the deathmatch flags
// and the body ques.
entity self; // the entity the function is executing for
entity other; // the other object in an impact, not used for thinks
float time; // the current game time. Note that because the
// entities in the world are simulated sequentially,
// time is NOT strictly increasing. An impact late
// in one entity's time slice may set time higher
// than the think function of the next entity.
// The difference is limited to 0.1 seconds.
Execution is also caused by a few uncommon events, like the addition of a new client to an existing server.
There is a runnaway counter that stops a program if 100000 statements are executed, assuming it is in an infinite loop.
It is acceptable to change the system set global variables. This is usually done to pose as another entity by changing self and calling a function.
The interpretation is fairly efficient, but it is still over an order of magnitude slower than compiled C code. All time consuming operations should be made into built in functions.
A profile counter is kept for each function, and incremented for each interpreted instruction inside that function. The "profile" console command in Quake will dump out the top 10 functions, then clear all the counters. The "profile all" command will dump sorted stats for every function that has been executed.
afunc ( 4, bfunc(1,2,3));
will fail because there is a shared parameter marshaling area, which will cause the 1 from bfunc to overwrite the 4 allready placed in parm0. When a function is called, it copies the parms from the globals into it's privately scoped variables, so there is no collision when calling another function.
total = factorial(3) + factorial(4);
Will fail because the return value from functions is held in a single global area. If this really gets on your nerves, tell me and I can work around it at a slight performance and space penalty by allocating a new register for the function call and copying it out.
built in functions
------------------
void(string text) dprint;
Prints the string to the server console.
void(entity client, string text) cprint;
Prints a message to a specific client.
void(string text) bprint;
Broadcast prints a message to all clients on the current server.
entity() spawn;
Returns a totally empty entity. You can manually set everything up, or just set the origin and call one of the existing entity setup functions.
Searches the server entity list beginning at start, looking for an entity that has entity.field = match. To start at the beginning of the list, pass world. World is returned when the end of the list is reached.
<FIXME: define all the other functions...>
gotchas
-------
The && and || operators DO NOT EARLY OUT like C!
Don't confuse single quoted vectors with double quoted strings
The function declaration syntax takes a little getting used to.
Don't forget the ; after the trailing brace of a function initialization.
Don't forget the "local" before defining local variables.
There are no ++ / -- operators, or operate/assign operators.
